2017 Volume 71 Issue 1 Pages 74-80
This study investigates the effects of types of superplasticizer and chemical compositions of blast furnace slag on hydration reaction of blended cement containing high volume of blast furnace slag. The hydration reaction of the high-volume blast furnace slag cements were strongly retarded when the superplasticizers containing lignosulfonates or gluconates were added. On the other hand, the addition of poly-carboxylate based superplasticizer had less effect on the retardation of hydration reaction. It was assumed that superplasticizer decreases the solubility of cement and disturbs the reaction of slag. And the retardation of hydration increased with increasing an amount of superplasticizers.
With the increase of Al2O3 contents in blast furnace slag, the time of secondary peak shown in heat flow curve became faster for the blended cements containing 90wt％ of slag, whereas the time of secondary peak for the blended cements with 70wt％ of slag was almost same. And this trend occurred clearly when it using superplasticizer, compare with no use. The reason for the difference in hydration reaction was estimated that amount of hydrates are different formed at early age for the blended cement containing higher volume of slag and the trend of hydration reaction at later stage is change from early age.
